From: Eric W. Biederman The ramdisk_blocksize option has been broken for quite a while in 2.6. Making an initrd with a 4K ext2 filesystem impossible to use. After digging into this, the problem turned out to that rd.c was not setting the hard sector size. There were a few secondary problems like i_blkbits was not being set, and the number KiB in uncompressed ext2 images was not taking into account the block size. I have also corrected the surrounding comments as they were not just incorrect but misleading. Signed-off-by: Andrew Morton --- 25-akpm/drivers/block/rd.c | 9 +++++++-- 25-akpm/init/do_mounts_rd.c | 20 +++++++++++++------- 2 files changed, 20 insertions(+), 9 deletions(-) diff -puN drivers/block/rd.c~fix-4k-ext2fs-support-in-26-initrds drivers/block/rd.c --- 25/drivers/block/rd.c~fix-4k-ext2fs-support-in-26-initrds Tue Aug 17 14:53:56 2004 +++ 25-akpm/drivers/block/rd.c Tue Aug 17 14:53:56 2004 @@ -349,13 +349,17 @@ static int rd_open(struct inode *inode, if (rd_bdev[unit] == NULL) { struct block_device *bdev = inode->i_bdev; struct address_space *mapping; + unsigned bsize; int gfp_mask; inode = igrab(bdev->bd_inode); rd_bdev[unit] = bdev; bdev->bd_openers++; - bdev->bd_block_size = rd_blocksize; - inode->i_size = get_capacity(rd_disks[unit])<<9; + bsize = bdev_hardsect_size(bdev); + bdev->bd_block_size = bsize; + inode->i_blkbits = blksize_bits(bsize); + inode->i_size = get_capacity(bdev->bd_disk)<<9; + mapping = inode->i_mapping; mapping->a_ops = &ramdisk_aops; mapping->backing_dev_info = &rd_backing_dev_info; @@ -449,6 +453,7 @@ static int __init rd_init(void) goto out_queue; blk_queue_make_request(rd_queue[i], &rd_make_request); + blk_queue_hardsect_size(rd_queue[i], rd_blocksize); /* rd_size is given in kB */ disk->major = RAMDISK_MAJOR; diff -puN init/do_mounts_rd.c~fix-4k-ext2fs-support-in-26-initrds init/do_mounts_rd.c --- 25/init/do_mounts_rd.c~fix-4k-ext2fs-support-in-26-initrds Tue Aug 17 14:53:56 2004 +++ 25-akpm/init/do_mounts_rd.c Tue Aug 17 14:53:56 2004 @@ -122,7 +122,8 @@ identify_ramdisk_image(int fd, int start printk(KERN_NOTICE "RAMDISK: ext2 filesystem found at block %d\n", start_block); - nblocks = le32_to_cpu(ext2sb->s_blocks_count); + nblocks = le32_to_cpu(ext2sb->s_blocks_count) << + le32_to_cpu(ext2sb->s_log_block_size); goto done; } @@ -173,10 +174,15 @@ int __init rd_load_image(char *from) } /* - * NOTE NOTE: nblocks suppose that the blocksize is BLOCK_SIZE, so - * rd_load_image will work only with filesystem BLOCK_SIZE wide! - * So make sure to use 1k blocksize while generating ext2fs - * ramdisk-images. + * NOTE NOTE: nblocks is not actually blocks but + * the number of kibibytes of data to load into a ramdisk. + * So any ramdisk block size that is a multiple of 1KiB should + * work when the appropriate ramdisk_blocksize is specified + * on the command line. + * + * The default ramdisk_blocksize is 1KiB and it is generally + * silly to use anything else, so make sure to use 1KiB + * blocksize while generating ext2fs ramdisk-images. */ if (sys_ioctl(out_fd, BLKGETSIZE, (unsigned long)&rd_blocks) < 0) rd_blocks = 0; @@ -184,7 +190,7 @@ int __init rd_load_image(char *from) rd_blocks >>= 1; if (nblocks > rd_blocks) { - printk("RAMDISK: image too big! (%d/%ld blocks)\n", + printk("RAMDISK: image too big! (%dKiB/%ldKiB)\n", nblocks, rd_blocks); goto done; } @@ -211,7 +217,7 @@ int __init rd_load_image(char *from) goto done; } - printk(KERN_NOTICE "RAMDISK: Loading %d blocks [%ld disk%s] into ram disk... ", + printk(KERN_NOTICE "RAMDISK: Loading %dKiB [%ld disk%s] into ram disk... ", nblocks, ((nblocks-1)/devblocks)+1, nblocks>devblocks ? "s" : ""); for (i = 0, disk = 1; i < nblocks; i++) { if (i && (i % devblocks == 0)) { _